Metro Vancouver Has Two Starts to Summer — Here's Why
Environment Canada marks meteorological summer from June 1, while the summer solstice on June 21 signals astronomical summer.
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Metro Vancouver — like much of the Northern Hemisphere — celebrates two starts to summer, depending on which calendar you follow.
Environment Canada defines meteorological summer as June 1 through August 31. This date marks the beginning of the warmest three-month period of the year in the Northern Hemisphere, making it useful for climate data and weather forecasting.
The other summer milestone is the summer solstice, which falls on June 21 this year. Astronomical summer runs from June 21 through September 22 and marks the longest day of the year — when the Northern Hemisphere is tilted closest to the sun.
Neither is "correct" — it simply depends on which metric you're using. The summer solstice has its opposite in winter: the winter solstice marks the year's shortest day and longest night.
Heat waves don't follow either calendar exactly. The devastating 2021 heat dome, British Columbia's most deadly weather event, occurred after both summers had technically begun. Severe heat can arrive as early as May or linger into September, though extreme temperatures are less likely outside the peak summer months. Similarly, extreme cold can occur after winter officially ends, though it tends to be less severe.